iPhone help if you can. [View all]

I have an iPhone8 help that is serving me well. In the past 2 weeks or so, the screen is always black. Very hard to read anything. I went to ..settings.. and made sure it was set to "light. It still is almost black. I have to use a magnifying glass to read anything that appears.
If I go to the local iPhone repair shop for help, they will charge me $30 to answer my question and $ 60 per hour for any repair.
I have gone to
settings and it always shows "light" and the screen is still so dark I can not, without a magnifying glass under light to read anything.
Is there a way I can lock it so the background stays"light" always?
Please let me know if you have had this problem. It started about 2 weeks ago. I have no idea what to do.
Thanks for any ideas, I'm a iPhone/computer idiot and need help.
Appreciate any help you can give me.